Input: Pass --no-playlist for YoutubeDl (#168)

If a link such as [this](https://www.youtube.com/watch?v=ygY2qObZv24&list=RDygY2qObZv24)
is passed to `YoutubeDl` without the option, it would cause a deadlock
in my bot.

There were many videos where it produced a `Silent` packet first instead
of mixed or passthrough. The URL I added was one that produced a
passthrough packet so I used that. Please let me know if this is wrong.

src/input/input_tests.rs

@@ -60,7 +60,7 @@ pub async fn track_plays_base<T, F>(
 
     // post-conditions:
     // 1) track produces a packet.
-    // 2) that packet is passthrough.
+    // 2) that packet is passthrough/mixed when we expect them to.
     let pkt = t_handle.recv_async().await;
     let pkt = pkt.raw().unwrap();